Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

Currently viewing:

Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1987
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well conducted and reported study in the peer-reviewed literature
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1989
Report Date:
1988

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
- Dams dosed from Gestation Days 1 to 19 as opposed to 6 to 15
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Reagent grade SBA (> 99%) was obtained from Curtin Matheson Scientific (Cincinnatti, OH)

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
* Pathogen-free animals (body weight 176-200 g for females, >300 g males)
* individually caged
* food and water: ad libitum
* room temperature: 22-26C
* relative humidity: 40-60%

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure (if applicable):
not specified
Vehicle:
unchanged (no vehicle)
Details on exposure:
Whole body inhalation chambers, continuously monitored and hourly concentrations recorded. Animals were left in the chambers after the 7-hour exposure period for degassing for 30 minutes prior to being placed back into individual cages.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
NIOSH method 1977 S53 was used to test SBA concentrations by gas chromatography. Chamber concentrations monitored with a Miran 14 general purpose infrared analyzer.
Details on mating procedure:
Single pairs were mated and each morning cage bottoms examined for evidence of sperm plugs or vaginal smears were taken. Females with sperm plugs were assigned as gestation day 0 and individually housed.
Duration of treatment / exposure:
Gestation days 1-19
Frequency of treatment:
7 hours/day
Duration of test:
20 days
Doses / concentrationsopen allclose all
Dose / conc.:
0 ppm
Dose / conc.:
3 500 ppm
Remarks:
10,605 mg/m3
Dose / conc.:
5 000 ppm
Remarks:
15,150 mg/m3
Dose / conc.:
7 000 ppm
Remarks:
21,210 mg/m3
No. of animals per sex per dose:
15-20 sperm positive females assigned to groups
Control animals:
yes, sham-exposed
Details on study design:
Weekly food and water intake, along with maternal weights, were measured on gestation days 0, 7, 14 and 20. Females were also weight each morning for the first week of exposures. From gestation days 1 to 19, exposures were conducted 7 hours/day and the animals were left in the chambers for degassing for approximately 1/2 hour after vapor generation was terminated. On gestation day 20, pregnant females were individually weighed and euthanized by CO2 asphyxiation.

Examinations

Maternal examinations:
* Food intake
* Water intake
* Body weight
* Clinical signs
Ovaries and uterine content:
* Corpora lutea
* Resorptions
* Live fetuses
Fetal examinations:
* Skeletal exam
* Visceral exam
* Body weight
* Sex of fetus
Statistics:
Maternal body weight and maternal food and water intake: Multivariate analysis
Corpora lutea: Kruskal-Wallis
Fetal weights: ANOVA
Fetal internal and external examinations: Fisher's Exact Test
Fetal group comparisons (litter size, percent alive/litter, percent normal/litter, percent females/litter: Kruskal-Wallis
Significance level: p < 0.05
Indices:
* Corpora lutea/litter
* Resorptions/litter
* Live fetuses/litter
* % female
Historical control data:
Not provided

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
7000 ppm 2-butanol produced narcosis in all animals, and they had not recovered completely the following day. Rats exposed to 5000 ppm were partially narcotized, with locomotor activity impaired. At 3500 ppm, animals were not visibly affected.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Weight gain was significantly reduced by all three concentrations. Significant reduction appeared to occur at the highest concentration (7000 ppm) for all three weeks, but only for weeks 1 and 3 at the two lower concentrations.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Food consumption was reduced in all treatment groups. Mean maternal feed intake was 126 +/- 15 g, 113 +/- 13 g, 112 +/- 17 g and 99 +/- 11 g for controls, 3500 ppm, 5000 ppm and 7000 ppm dose groups, respectively, at week 3.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Water intake increased as pregnancy progressed and was generally higher, though not significantly, in treatment groups than in controls.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
Narcosis and impairment of locomotor activity at 7000 ppm.
Partial narcosis at 5000 ppm.
No effect at 3500 ppm.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Details on results:
Some evidence for maternal toxicity was observed with exposures to 2-butanol. Doses higher at or higher than 5000 ppm caused narcosis and locomotor effects. Body weights were statistically significantly reduced in all treatment groups, relative to control.

Maternal developmental toxicity

Number of abortions:
not specified
Pre- and post-implantation loss:
not specified
Total litter losses by resorption:
effects observed, treatment-related
Description (incidence and severity):
Statistically significant increase in the number of resorptions per litter was reported at 7,000 ppm (3.8±2.2) compared with the control (1.5±1.3) (Table 1).
Early or late resorptions:
not specified
Dead fetuses:
effects observed, treatment-related
Description (incidence and severity):
A statistically significant decrease in live fetuses/litter was observed at 7000 ppm (Table 1).
Changes in pregnancy duration:
not examined
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not specified
Changes in number of pregnant:
not specified
Other effects:
not specified
Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Weight gain was reduced at all dose concentrations, but only achieved statistical significance at the mid- and high-doses. Statistically significant decrease in food consumption noted starting at the lowest dose.

Effect levels (maternal animals)

Dose descriptor:
LOAEC
Effect level:
3 500 ppm
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Maternal abnormalities

Abnormalities:
effects observed, treatment-related
Localisation:
other: body weight, food intake.
Description (incidence and severity):
Weight gain was reduced at all dose concentrations, but only achieved statistical significance at the mid- and high-doses. Statistically significant decrease in food consumption noted starting at the lowest dose.

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Fetal weights were reduced in all 2-butanol-exposed groups; differences were statistically significant when compared to the control at 5,000 and 7,000 ppm (see Table 1).
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): not specified
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
A statistically significant decrease in live fetuses/litter was observed at 7000 ppm (Table 1).
Changes in sex ratio:
no effects observed
Description (incidence and severity):
There was no effect on the percentage of females/litter (see Table 1).
Changes in litter size and weights:
not specified
Changes in postnatal survival:
not specified
External malformations:
no effects observed
Description (incidence and severity):
External fetal malformations were not observed.
Skeletal malformations:
effects observed, treatment-related
Description (incidence and severity):
A statistically significant increase in the incidence of pooled skeletal variations was observed at 7,000 ppm (100%) when compared to controls (32%). The authors indicated that the majority of skeletal malformations were rudimentary cervical ribs (see Table 1). The authors also indicated that variations seen were typical of fetotoxicity, particularly reduced ossification.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Occassional visceral malformations (e.g. ventricular septal defect, hydronephrosis) were seen, as were variations (e.g. enlarged brain ventricules, dilated renal pelvis), but the incidences were not significantly affected by treatment with 2-butanol (see Table 1).
Other effects:
not specified
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There was no increase in the incidence of fetal malformations at any concentration. An increase in resorptions and decrease in live fetuses/litter was seen at the highest concentration (7000 ppm), and a decrease in fetal weight was seen at 5000 ppm.

Effect levels (fetuses)

open allclose all
Dose descriptor:
NOAEC
Effect level:
ca. 3 500 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: fetal weight
Dose descriptor:
NOAEC
Effect level:
ca. 5 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reduction in number of live offspring
other: resorptions/litter, pooled number of skeletal variations

Fetal abnormalities

Abnormalities:
effects observed, treatment-related
Localisation:
skeletal: rib

Overall developmental toxicity

Developmental effects observed:
no

Any other information on results incl. tables

Table 1. Fetal observations after exposure to SBA

 Parameter  0 ppm  3500 ppm  5000 ppm  7000 ppm
 No. Pregnant/No. bred  15/16  16/16  14/15  11/15
 Corpora lutea/litter  16  17  16  16
 Resorptions/litter 1.5   1.6  1.5  3.8*
 Live fetuses/litter  14  15  14  10*
 Fetal weight (g) - male  3.1 2.9 2.6* 1.4*
 Fetal weight (g) - female 3.3 3.1 2.7* 1.5*
 Skeletal
 No. examined (fetuses) 15 (102)  14 (104) 14 (93) 11 (53) 
 No. malformations  1 (1)  1 (1)  4 (4)  2 (2)
 No. variations  13 (33)  13 (40)  12 (32)  11 (53)*
 % normal fetuses  99  99  95  97
 Visceral        
No. examined  15 (106) 14 (105) 14 (98)  11 (57)
  No. malformations  1 (2) 1 (1)  2 (4) 1 (1)
 No. variations 3 (3)   7 (14)   6 (14)  11 (52)
 % normal fetuses   98  99  96  98

* p < 0.05

Applicant's summary and conclusion

Conclusions:
Secondary butanol was not teratogenic to rats exposed up to 7000 ppm, but caused embryo and fetotoxicity at concentrations which significantly reduced maternal body weight gain and food consumption.
Executive summary:

Groups of 15 to 20 sperm-positive rats were exposed to secondary butanol at concentrations of 0, 3500, 5000, or 7000 ppm, 7 hours/day, throughout gestation. No treatment-related malformations were observed at any dose. Maternal food consumption was reduced in all treatment groups. Maternal body weights were significantly reduced at the mid- and high-doses only. Fetal body weights were reduced at the mid- and high-dose level. Resorptions were increased at the highest concentration and the number of live fetuses/litter was reduced also at the highest concentration. The NOAEC for developmental toxicity in this study was 3500 ppm, and the LOAEL for maternal toxicity was 3500 ppm.